In "Word Focus" Glenn McClure writes:

A good summary of the implications of propitiation is given by D. M. Lloyd-Jones: “Propitiation carries this notion that there is someone who has been offended, someone who has done the offending, that there is an offence, and that something is necessary on both sides. . . . This great and glorious doctrine teaches us that the very God whom we have offended has Himself provided the way whereby the offence has been dealt with.”

Source: Studies in the Psalms: Adult Teacher's Insights, page 10.